Needle electromyography and histopathologic correlation in myopathies |
| |
| Authors: | Ugur Sener MD Jennifer Martinez-Thompson MD Ruple S Laughlin MD Elliot L Dimberg MD Devon I Rubin MD |
| |
| Institution: | 1. Mayo Clinic Neurology Department, 4500 San Pablo Road South, Jacksonville, Florida, 32224, USA;2. Mayo Clinic, Rochester, Minnesota, USA |
| |
| Abstract: | Introduction: The molecular mechanism of immune-mediated necrotizing myopathy (IMNM) remains unknown. Autophagy impairment, described in autoimmune diseases, is a key process in myofiber protein degradation flux and muscle integrity and has not been studied in IMNM. Methods: Muscle biopsies from patients with IMNM (n = 40), dermatomyositis (DM; 24), polymyositis (PM; 8), polymyositis with mitochondrial pathology (4), sporadic inclusion body myositis (8), and controls (6) were compared by immunohistochemistry. Results: The proportions of myofibers containing autophagy markers LC3b and p62 were higher in IMNM than in DM or PM and correlated with creatine kinase levels. In IMNM, compartmentalized LC3b puncta were located in regenerating and degenerating myofibers surrounded by major histocompatibility complex type II+ inflammatory cells. Several IMNM myofibers accumulated ubiquitin and misfolded protein. Discussion: The detection of LC3b+ or p62+ myofibers could be used in differentiating IMNM from PM. The identification of autophagy-modifying molecules potentially could improve patients’ outcomes. Muscle Nerve, 2019 |
| |
| Keywords: | EMG fibrillations muscle biopsy muscle pathology myotonic discharges short motor unit potentials |
|
|
